ABSTRACT: 2-aminothiazole is one of privileged structure which finds applications in number of
pharmaceuticals like antiviral, antibacterial, antifungal, antituberculous, antibody and antifungal agents. The
2-aminothiazole nucleus is a recurring scaffold in compounds of pharmaceutical interest. Complexes of Schiff
bases derived from 2-aminothiazole have been studied vastly. The complexes were characterized by elemental
(C, H, N and metal) and spectral (UV-visible and IR) analysis, magnetic susceptibility and conductivity
measurements and evaluation of biological activities. The complexes possess specific geometry. Various ligand
field parameters of complexes can be studied. The Schiff bases derived from aminothiazoles and their transition
metal complexes are expected to be biologically active compounds.

KEYWORDS : 2-aminothiazole, biological activity, Schiffs base, Metal complexes,
I.
INTRODUCTION
Coordination chemistry is prime branch of inorganic chemistry. A number of reviews are published in
literature, which throws light on research and development of made in the field of coordination chemistry [1]. It
is one of the rare research topics where material scientists, biological scientists and coordination chemists work
together. The coordination compounds of ligands containing nitrogen, oxygen and sulphur as the donor atoms
exhibit a wide spectrum of biological activities.

Presence of exocyclic nitrogen, cyclic sulphur & nitrogen & π electrons in the ring gives coordination
ability to 2-aminothiazole Among these ligands Schiff bases attract the attention of researchers mainly due to
their facile syntheses, easily availability, electronic properties and good solubility in common solvents.
Azomethine compounds or Schiff bases are typically formed by condensation of a primary amine and aldehydes
or ketones and first reported by Schiff [2]. Schiff bases were used as starting material for the synthesis of various
bioactive heterocyclic compounds [3]. Among the Schiff bases, thiazole containing Schiff bases are important
due to their wide applications as antimicrobial, anti-inflammatory, anti-degenerative and anti-HIV agents, drugs
[4-5]. Thiazoles and their derivatives form a part of vitamin B1 and coenzyme carboxylase. Metal complexes
with these ligands are becoming increasingly important as biochemical, analytical and antimicrobial reagents in
the design of molecular models and material chemistry [6-8].The use of microwaves in organic synthesis has
recently gained in importance [9]. Microwave irradiated reactions under solvent free or less solvent conditions
are used for carrying out chemical transformations, which are pollution free, eco-friendly, low cost and offer
high yields together with simplicity in processing and handling [10-12]. Microwave systems provide the
opportunity to complete complex reactions in minutes. The salient features of microwave approach are shorter
reaction times, simple reaction conditions and enhancements in yields [13-16]. Microwave assisted synthesis
is presented as a very useful tool in coordination chemistry. The synthesis assisted by microwave radiation has

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Thiazole Containing Schiffs…
proven to be an excellent tool for the achievement of new structural types of polynuclear transition metal
complexes [17].

II.

RELATED WORK & IMPORTANCE

Schiff base metal complexes are well studied in past. In the present work microwave assisted synthesis,
characterization and applications of thiazole containing Schiff base transition metal complexes is discussed.
Kablka et. al. [18] synthesized 2-aminothiazoles by condensation of α-bromo-ketones with thiourea through
microwave assisted approach. They found that condensation of α-bromo-ketones with thiourea gives desired
product within five minutes under microwave irradiation in absence of catalysts. Meshram et. al. [19] reported
2-aminothiazole derivatives by N-methylimidazole catalyzed cyclization of α-halo ketone carbonyls with
ammonium thiocyanate in water–alcoholic media. Schiff base from 4-acetyl-3-methyl-1-phenyl-2-pyrazolin-5one with 2-amino-4-phenyl thiazole was synthesized and characterized by elemental analysis, mass spectra, 1H
NMR spectra, 13C NMR spectra and F.T.IR spectra by K.S. Pandya et. al. [20]. Ali et. al. [21] have been
synthesized two series of l,n-alkylene glycol di[4{N(2-thiazoIylazo- methinyl)}2-methoxy] phenyl ether and l,nalkylene glycol di[4{N(2-benzo-thiazolylazomethinyl)} 2-methoxy]phenyl ether, via reactions 2-aminothiazole
and 2-aminobenzothiazole with dialdehyde (which are synthesized from reaction vanillin with l, n-dibromo or
chloro alkane in the basic media). The new compounds were characterized by elemental analysis, physical and
spectral data. All the Schiff-bases were found to be antibacterial and antifungal.Jordan et. al. [22] have been
studied thermal decomposition of 2-aminothiazole (2-amt) complexes of general formula M(2-amt)2X2, [M =
Co(II) and Cu(II)] and Ni(Z-amt)4X2, [X = Cl and Br] in air and argon by TG and DTG as well as by DTA in
nitrogen; end products from the decompositions in air have been characterized by X-ray powder diffraction.
Siddiqui et. al. [23] have been synthesized Schiff bases derived from o-formylphenoxyacetic acid and a series of
aminothiazoles to form a number of potentially biologically active compounds. The structures of these Schiff
bases have been characterized using IR and 1H and 13C-NMR spectroscopy. 2-aminophenylthiazole derivatives
were synthesized and characterized by FTIR by Singh and coworkers [24]. All the synthesized 2aminophenylthiazol derivatives were tested for their antibacterial and antifungal activity. Pattan et. al. [25] have
been synthesized some substituted thiazoles. These compounds were evaluated for various biological activities
like Anti-diabetic, anti-inflammatory and anti-fungal activity. Novel Schiff bases derived from some hetero
cyclic β-diketones with 4-phenyl-2-aminothiazole have been synthesized and characterized by Elemental
analysis, FT-IR, 1H NMR, 13C NMR, Mass spectra, TGA analysis and UV spectra by Thakar et. al. [26].
Schiff bases and their Co(II), Ni(II) and Cu(II) complexes formed by the condensation of
2-acetonaphthone with 2-Amino-4-chlorophenol (AACP), 2-amino-4- methylbenzothiazole (AABT) and
2-aminothiazole (ACAT) have been synthesized by Mishra et. al. [27]. These compounds have been
characterized by elemental analysis, FT-IR, FAB- mass, molar conductance, electronic spectra, ESR and
magnetic susceptibility.
More et. al. [28] have been reported Co(II) and Zn(II) complexes of Schiff bases derived from 4-(pfluorophenyl)-2-aminothiazole and o-hydroxyaldehydes (substituted salicylaldehyde, o-vanillin and 2-hydroxy1-naphathaldehyde) . The complexes were characterized by elemental (C, H, N and metal), spectral (UV-visible
and IR) analyses, magnetic susceptibility, conductivity measurements and evaluation of biological activities.
N-(thiophen-2-ylmethylene)benzo[d]thiazol-2-amine Schiff base (L) derived from 2-aminobenzothiazole and 2thiophenecarboxaldehyde was synthesized and characterized using elemental analysis, IR, mass spectra, 1H
NMR and UV–Vis spectra. Complexes are tested for antitumor activity by S. Eldin et. al.[29]. Thakar and
coworkers [30] have been synthesized Transition metal complexes of Cr(III), Mn(II), Fe(II), Co(II), Ni(II) and
Cu(II) metal ions with the Schiff base derived from the condensation of 2-amino-4(4’-phenyl/methylphenyl)-5methyl-thiazole with 4-acetyl-1(3-chloro phenyl)-3-methyl-2-pyrazoline-5-ones. The complexes were
structurally characterized by elemental analysis, molar conductance measurements, magnetic susceptibility
measurements and spectral techniques like IR, UV, 1H NMR, 13C NMR and Mass Spectra. Complexes have
been screened for their antifungal and antibacterial activities. Wang et. al. [31] have synthesized cobalt (II) and
nickel (II) complexes of 2-aminothiazole with demethylcantharate. These Complexes were characterized by
elemental analysis, infrared spectra and thermogravimetric analysis. Synthesis and study of TiO 2 chemically
modified by Pd (II) 2-aminothiazole complex for phenol degradation at different pH values were performed by
Cristante et. al. [32] Pandya et. al. [33] have studied Schiff bases and their metal complexes derived from some
hetero cyclic β-diketones with 4-phenyl-2-aminothiazole. All the synthesized compounds were confirmed for
their structure by Elemental analysis, FT-IR, 1H NMR, 13C NMR, Mass spectra, TGA analysis and UV spectra.
Metal complexes show moderate antibacterial activity. Metal complexes of Cr(III), Co(II), Ni(II) and Cu(II)
with the Schiff bases derived from N- (4-chlorobenzylidene)-5-methyl-1,3-thiazol-2-amine and N-[4(dimethylamino) benzylidene]-6-nitro-1,3-benzothiazol-2-amine have been synthesized by conventional as well
as microwave methods by Jain et. al. [34]. Compounds have been characterized by elemental analysis, FT-IR,

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Thiazole Containing Schiffs…
FAB-mass, molar conductance, electronic spectra, ESR, magnetic susceptibility, thermal, electrical conductivity
and XRD analysis.
Kelode et. al. [35] has been prepared Schiff base by the condensation of 2 hydroxy-5-chloro-3-nitro
acetophenone and thiazole. Metal complexes with Co(II), Ni(II), Cu(II), Cr(III), Mn(III), Fe(III), Zr(IV) and
UO2(VI) have been prepared and characterized by elemental analysis, conductance measurements, molecular
weight determinations, spectral and thermal studies.New ruthenium carbonyl complexes of N-[(2pyridyl)methylidene]-2-aminothiazole formed by reaction between bidentate Schiff base ligands derived by the
condensation of pyridine-2-carboxaldehyde with 2-aminothiazole in a 1:1 mole ratio in acetonitrile and
ruthenium carbonyls, [Ru(CO)2Cl2]n/[Ru(CO)4I2]. Complexes having general formula [Ru(CO)2(L)X2] (X = Cl
(1) and I (2)) (L = N- [(2-pyridyl)methylidene]-2-aminothiazole) have been reported by Mondal et. al. [36].
Catalytic activity of these compounds were investigated to the oxidation of PhCH2OH to PhCHO, 2-butanol
(C4H9OH) to 2-butanone, 1-phenylethanol (PhC2H4OH) to acetophenone, cyclopentanol (C5H9OH) to
cyclopentanone, cyclohexanol to cyclohexanone, cycloheptanol to cycloheptanone and cycloctanol to
cycloctanone using N-methylmorpholine-N-oxide (NMO) as oxidant. Schiff base metal complexes of Co(II),
Ni(II) and Cu(II) derived from 4-chlorobenzylidene-2-aminothiazole and 2- nitrobenzylidene-2-aminothiazole
have been synthesized by conventional as well as microwave methods. These compounds have been
characterized by Mishra et. al. [37] by using elemental analysis, FT-IR, FAB-mass, molar conductance,
electronic spectra, ESR, magnetic susceptibility, thermal, electrical conductivity and XRD analysis.Gupta and
coworkers [38] synthesized Schiff base complexes of Cr(III), Co(II), Ni(II) and Cu(II) derived from 5bromosalicylaldehyde with 2-amino-5-nitrothiazole and 4-dimethylaminobenzaldehyde with 2-amino-3hydroxypyridine by conventional as well as microwave methods. These compounds have been characterized by
elemental analysis, FT-IR, FAB-mass, molar conductance, electronic spectra, 1H-NMR, ESR, magnetic
susceptibility, thermal, electrical conductivity and XRD analysis.Schiff bases derived from Various substituted
acetophenones on treatment with iodine and thiourea yielded 2-amino-4-(substituted-phenyl)-thiazole which
on further treatment with various substituted aldehydes gave N-(substitutedbenzylidene)-4(substitutedphenyl)thiazol-2-amine. All the synthesized compounds were characterized by FTIR, 1H NMR and
Mass data. Synthesized compounds were screened for antibacterial (S. aureus, E. coli, P. aeruginosa) and
antifungal (C. albicans, A. flavus, A. fumigatus) activities by Gupta et. al. [39].

III.

CONCLUSION

Microbial infections remain the major cause of death over the world. Emergence of multi-drug resistant
to different infectious organisms like M.tuberculosis made the condition most alarming. Therefore, there is an
urgent demand for a new class of antimicrobial agent with a different mode of action and it led medicinal
chemists to explore a wide variety of chemical structures. Among the Schiff bases, thiazole containing Schiff
bases and their metal complexes are important due to their remarkable antimicrobial activities. Hence it is
worthwhile to study the synthesis of Schiff bases and their metal complexes of thiazoles for various
applications.